Generally, there are three methods for treating cancer: surgical operation, a radiation therapy, and drug treatment. Each method may be used alone, or in combination of two or more methods for treating cancer. Many early stage cancers may be treated by surgical operation, but in case where cancer is much advanced, or metastasis is generated, the treatment is difficult with the surgical operation alone, and a method such as a radiation therapy or drug treatment should be carried out together.
The radiation therapy is to irradiate cancer cells with X-rays or γ-rays, wherein the emitted rays may be used in a surgically inoperable region, or cancer cells having especially good reactivity to radiation, or used before or after surgery. Further, drug treatment is to adopt a method of destructing DNA or enzyme required for the proliferation of cancer cells by administrating a cytotoxic agent orally or by injection. Particularly, the advantage of the drug treatment over the surgical operation or the radiation therapy is to enable a drug to reach any cancer site in the body, and metastatic cancer to be treated, and for this reason, the drug treatment has been widely used as a standard therapy for metastatic cancer treatment. Of course, the drug treatment may not lead the metastatic cancer to be completely cured, but lead symptoms to be relieved, thereby playing an important role in improved quality of life and life extension of patients.
Generally, for drug treatment, chemotherapy using a poorly water-soluble drug such as doxorubicin, cisplatin, taxol, 5-fluorouracil and the like has been widely used so far, but it has a limitation in administration. Since those drugs are poorly water-soluble, even administration of a curable amount may cause severe pain to the patients, and due to excessive side effects, currently the drugs may not be administrated in a large amount. Cause of such side effects is non-selectivity of an anticancer agent, that is, the anticancer agent acts on not only cancer cells, but also normal cells, thereby not killing only cancer cells, but inhibiting growing and causing necrosis of normal cells, and thus, the patients may be seriously pained.
To this end, a delivery system such as micelles and liposomes is prepared to be used to deliver a poorly water-soluble anticancer agent, wherein when the delivery system is prepared, an anticancer agent is added to be contained within the delivery system.
Recently, solid lipid nanoparticles (SLN) which are a delivery system similar to low density lipoprotein (LDL) implementing a natural carrier without causing an immune reaction unlike micelles and liposomes are used as the delivery system for delivering an anticancer agent, wherein the low density lipoprotein (LDL) is basically involved in lipid and protein mobilization, specifically cholesterol delivery to external tissues of a liver in entire systemic circulation. In practice, a non-hydrophilic drug such as cyclosporine A and amphotericin B lipid complex salt (ABLC) was effectively delivered by binding the drug to LDL in pre-clinical or clinical treatment.
However, since a method of separating natural low density lipoprotein (LDL) from blood is too complicated and time-consuming, solid lipid nanoparticles which are a biomimetic model of the low density lipoprotein (LDL) have been developed from cholesteryl ester and phospholipid, instead of not containing apolipoprotein.
However, a delivery system which is the existing solid lipid nanoparticles, is absorbed in a phagocyte present in a liver, or released in a short time by a kidney, thereby not sufficiently delivering an anticancer agent encapsulated therein to a cancer tissue, and thus, it is problematic due to a limitation in an effective anticancer treatment.